This invention relates to a protective and support assembly, including an electrically non-conductive holder and a shield, for a glow type electric igniter.
A glow type electric igniter is a device which in response to an electrical input generates a thermal output within a temperature range suitable, for example, for the ignition of a fuel, such as natural or artificial gas or the like. Thus, such igniters have utility in ranges, ovens, dryers, furnaces and similar appliances and devices utilizing such a fuel and offer susceptibility to ignition in the manner to be described.
One type of igniter is formed of silicon carbide as disclosed, for example, in U.S. Pat. Nos. 3,372,305 and in 3,397,375. Another type of igniter comprised of molybdenum disilicide is disclosed in U.S. Pat. Nos. 3,488,133 and in 3,823,345. The instant invention will be described in more detail below with reference to an igniter assembly that incorporates an igniter which exhibits the properties of silicon carbide; however, it is intended that the principles of the invention may be applied to igniters which exhibit the properties of molybdenum disilicide as well as to other types of igniters in respect of the material of which the igniter is made.
Several difficulties have been experienced with the silicon carbide and molybdenum disilicide igniters, such as those disclosed in the above-mentioned patents, in the connection of the terminal parts of the igniter to a source of electric energy and in the support of the igniter in a location proximate a gaseous fuel burner, for example, to ignite the fuel therefrom. One problem with such igniters is that the igniters are fragile. Also, in certain applications the igniters are subject to extremely high temperatures, including those generated by the igniter itself as well as those ambient temperatures occurring in the environment within which the igniter is located, and the igniter electrical connections and mechanical supports must be capable of withstanding such high temperatures without damage to the same or the fragile igniter.
One arrangement for connecting electrical leads to the terminals parts of a high temperature gas igniter wherein respective metallized coatings are provided about the respective leads and terminal parts in conductive engagement bonding the same is disclosed in a U.S. patent application for "Gas Igniter," Ser. No. 290,256, Filed Sept. 18, 1972, now U.S. Pat. No. 3,842,319, issued Oct. 15, 1974, which is assigned to the same assignee as the instant application.
Moreover, a shock absorbent support and a protective shield primarily intended for a molybdenum disilicide igniter are disclosed in U.S. Pat. No. 3,823,345. in the latter patent, the support comprises a split housing support through which two terminal strips pass for external crimped connection to the respective terminal parts of the igniter at one end of the housing and for connection to a pair of wires at the other end of the housing, and the shield and housing parts are fastened together by a single screw. Also, in U.S. Pat. No. 3,562,590 an electric igniter wire is attached to a pair of electrodes that are fixedly mounted in a support plug, which is located in a hollow cylindrical casing, and the looped end of the igniter wire protrudes beyond the end of the casing to define an igniting portion for positioning proximate a gas burner.